With the increasing concern for safety, there is a positive move toward providing safe materials for public and household use. One particular area of need is that of providing flame-resistant or flame-retardant non-opaque products for use by the ultimate consumer. As a result of this demand, many products are being required to meet certain flame-retardant criteria both by local and federal government and the manufacturers of such products. One particular set of conditions employed as a measuring standard for flame retardancy is set forth in Underwriters' Laboratories, Inc. Bulletin 94. This Bulletin sets forth certain conditions by which materials are rated for self-extinguishing characteristics.
In the art, there are many known flame-retardant additives which are employed by mixing with products to render such materials self-extinguishing or flame retardant. Such flame-retardant additives have been known to be employed in amounts of 5 to 20 weight percent in order to be effective in extinguishing burning of those products which are combustible. It has also been found that such amounts can have a degrading effect upon the base product to be rendered flame retardant, resulting in the losses of valuable physical properties of the base product. This is particularly so when employing known flame-retardant additives with base product polycarbonate resins. Many of these known additives have a degrading effect upon the polymer.
In many instances, it is desirable that articles produced from these fire retardant polycarbonate resins retain their non-opaque characteristics.
From U.S. Pat. No. 3,926,908 to Victor Mark issued Dec. 16, 1975, flame-retardant polycarbonate compositions comprising in admixture, an aromatic carbonate polymer and a flame-retardant additive which may be the metal salts of sulfonic acids of aromatic ketones is disclosed.